Bi-directional transport of the nucleus by dynein and kinesin-1

Abstract

Proper transport and positioning of cell organelles often depends on the antagonistic activities of dynein and kinesin-1, two microtubule motors with opposite directionality.1 One of the largest known transport cargoes is the cell nucleus. Both dynein and kinesin-1 participate in positioning of the nucleus through binding to the nuclear envelope (NE).2-9 Surprisingly, both dynein and kinesin-1 can be recruited to the NE through multiple pathways, one involving SUN-KASH domain containing proteins and the other involving nuclear pore complexes (NPCs). Here, we discuss the molecular mechanisms of dynein and kinesin recruitment to the NE through NPCs, as well as the functional implications of dynein and kinesin-1 activity at the NE in mammalian cells. Finally, we discuss how motor activities at the NE might be controlled during the cell cycle.

Keywords: RanBP2; centrosome; dynein; kinesin; mitosis; nuclear envelope; spindle.

Figure 1

Movement of cargoes and the microtubule network during cargo transport. (A) Kinesin-1 associates with a vesicle and transports it towards the plus-end of a microtubule embedded in the centrosome. As the vesicle is small compared to the microtubule network, the vesicles is displaced relative to the microtubule network (large red arrow), while the microtubule network remains largely stationary (small yellow arrow). (B) Kinesin-1 associates with the nucleus and transports it towards the plus-end of a microtubule plus-end of a microtubule embedded in the centrosome. As the nucleus is very large, the nucleus and the microtubule network are displaced towards opposite sides (large blue and yellow arrows). In normal cells, dynein activity prevents separation of nucleus and centrosome, but in the absence of dynein activity (depicted here) kinesin-1 pushes centrosome and nucleus apart.